The Effect of Self-gravity of Gas on Gas Fueling in Barred Galaxies with a Supermassive Black Hole

In our previous paper, we have shown that a gas disk in the nuclear region of a barred galaxy which contains a central supermassive black hole (SMBH) rapidly evolves into a nuclear gas ring by the effect of an additional inner Lindblad resonance caused by the SMBH. In this paper, we investigate the fate of the gas ring, involving self-gravity of gas, using two-dimensional hydrodynamical simulations. We find that the gas ring becomes gravitationally unstable for a gas surface density of gas above a critical value, and fragments into several gas clumps. Some denser clumps increase their mass via the accretion of the surrounding gas and collisions with other clumps, and finally a very massive gas clump (10^7 M_sun) is formed. Due to the torque from the most massive clump, a part of the gas in the ring loses its angular momentum and falls into the galactic center. As a result, a nuclear gas disk (50 pc) is formed around the SMBH. The accretion rate for $R<50$ pc attains about 1 M_sun/yr for 3.5*10^7 yr. At the final phase of the bar-driven fueling, self-gravity is crucial for the angular momentum transfer of the gas. This is a new mechanism for gas fueling to the vicinity of the SMBH.Comment: 14 pages, 7 figures, AASTeX, submitted to Ap

Induced Pluripotent Stem Cells for Clinical Use

Induced pluripotent stem cells (iPSCs) are expected to be a novel cell source for regenerative medicine. Although iPSCs represented a significant breakthrough, there were many initial obstacles for their clinical use such as exogenous sequence insertions, inefficient cell reprogramming, tumorigenic properties, and animal-derived culture components. However, much progress has been made in iPSC generation since their development. The first human trial of iPSC-derived cell transplantation was conducted in September 2014, in which iPSC-derived retinal pigment epithelial cells were transplanted to a patient with macular degeneration. Because multiple clinical trials using iPSCs are expected in the near future, preparation of guidelines for generating and selecting iPSC lines suitable for clinical application is a pressing issue

Cardiac Innervation and Sudden Cardiac Death

The heart is extensively innervated and its performance is tightly controlled by the nervous system. Cardiac innervation density varies in diseased hearts leading to unbalanced neural activation and lethal arrhythmia. Diabetic sensory neuropathy causes silent myocardial ischemia, characterized by loss of pain perception during myocardial ischemia, which is a major cause of sudden cardiac death in diabetes mellitus (DM). Despite its clinical importance, the mechanisms underlying the control and regulation of cardiac innervation remain poorly understood

The Effect of a Central Supermassive black hole on the Gas Fuelling

When a supermassive black hole exists in the centre of a galaxy, an additional inner Lindblad resonance (ILR) exists inside the usual ILRs. We study gas dynamics in a weakly barred potential with a central supermassive black hole by using 2D numerical simulations, and we investigate the effect of the additional ILR on fuelling gas into nuclear starburst regions or AGNs. Our numerical results show that strong trailing spiral shocks are formed at the resonance region, and the gas in the shock region is rapidly fuelled into a central region and make a nuclear gas ring. As a result, a large amount of gas is concentrated in the nuclear region beyond the ILR in a dynamical time scale.Comment: 7 pages, 14 Postscript figures, LaTeX 2.09, requires mn.sty, to be published in MNRA

Induced Pluripotent Stem Cells in Cardiovascular Medicine

Induced pluripotent stem (iPS) cells are generated by reprogramming human somatic cells through the forced expression of several embryonic stem (ES) cell-specific transcription factors. The potential of iPS cells is having a significant impact on regenerative medicine, with the promise of infinite self-renewal, differentiation into multiple cell types, and no problems concerning ethics or immunological rejection. Human iPS cells are currently generated by transgene introduction principally through viral vectors, which integrate into host genomes, although the associated risk of tumorigenesis is driving research into nonintegration methods. Techniques for pluripotent stem cell differentiation and purification to yield cardiomyocytes are also advancing constantly. Although there remain some unsolved problems, cardiomyocyte transplantation may be a reality in the future. After those problems will be solved, applications of human iPS cells in human cardiovascular regenerative medicine will be envisaged for the future. Furthermore, iPS cell technology has generated new human disease models using disease-specific cells. This paper summarizes the progress of iPS cell technology in cardiovascular research

Pigs as Models of Preclinical Studies and In Vivo Bioreactors for Generation of Human Organs

Pigs are valuable and essential large animal models for human medical applications, including for stem cell therapy. Moreover, substantial effort has been made to directly engraft genetically engineered pig organs in the human body and to use pigs as in vivo bioreactors for the growth and development of human cells, tissue, or organs. However, engraftment of human cells in pigs has not yet been achieved. Although severe combined immunodeficient pigs have been developed, which can accept human biological materials, these pigs do not have practical value at present owing to difficulty in their care. To overcome these current limitations, we have proposed the generation of operational immunodeficient pig models by simply removing the thymus and spleen, enabling the long-term accommodation of human tissue. In this review, we summarize research progress on xenotransplantation animal models that accept human cells, tissues, or organs

A danger of induction of Brugada syndrome during pill-in-the-pocket therapy for paroxysmal atrial fibrillation

Rhythm control therapy by sodium channel blockers is widely performed for the treatment of paroxysmal atrial fibrillation. Here, we present a case of acquired Brugada syndrome by pill-in-the-pocket treatment using pilsicainide. It is important that this therapy should be applied only after confirming the drug safety to the patients